This invention relates to a process for preparing chlorotrifluoromethylbenzene. More particlarly, it relates to a process for preparing chlorotrifluoromethylbenzene by reacting chlorotoluene, hydrogen fluoride and chlorine in a gaseous phase in the presence of a certain specific catalyst.
Chlorotrifluoromethylbenzene is a known compound and useful as an intermediate in the production of medicines, dyes, agricultural chemicals, and the like.
For the production of p-chlorotrifluoromethylbenzene, there are known several processes including a process comprising reacting p-chlorotrichloromethylbenzene with hydrogen fluoride in the presence of aluminum fluoride (cf. Japanese Patent Publication (unexamined) No. 13052/1979) and a process comprising reacting p-chlorotoluene with chlorine and hydrogen fluoride in a gaseous phase at an elevated temperature (cf. Japanese Patent Publication (unexamined) No. 82728/1978). The latter process is superior to the former process since the starting material, i.e. p-chlorotrichloromethylbenzene, in the former process is prepared by chlorinating p-chlorotoluene. The latter process, however, has some disadvantages such that the reaction temperature is high and the selectivity is low.